Feeding powdered fuel



69% M I I y Nov. 20 1923. 1,474,613

M. w. ARROWOOD FEEDING POWDERED FUEL Filed May 26, 1919 2 Sheets-Sheet 1 Noin- 20, 1923. 1,474,613

M. w. ARROWOOD FEEDING POWDERED FUEL Filed May .26, 1919 2 Sheets-Sheet 2 MILTON W. ARROWOOD, OF CHICAGO, ILLINOIS, ASSIGNOR TO GROUND COAL ENGINEER- v 1,474, 13 PA'ENT FICE.

4 ING CORPORATION, OF WORCESTER, MASSACHUSETTS, A CORPORATION.

FEEDING rownnann FUEL.

Application filed May 2a, 1919. Seral"1i'o.-299,833,

To all whom it may cone-em:

Be it known that I, MILTON W. Armowooo, a citizen of the United States, residin at Chicago, in ,the county of Cook and rtate of Illinois, have invented certain new and useful Improvements in Feeding Powdered Fuel, of which the following is a specification.

This invention relates to the feeding of powdered fuel and more particularly to the feeding of powdered coal and thoroughly mixing therewith the requisite amount of air to produce efficient combustion.

One of the primary objects of my invention is the provision of a method and apparatus by which the powdered fuel is thoroughly diffused and mingled with the proper amount of air to effect complete combustion.

Another object of my invention is to mix the fuel with all of the air required for combustion before it is delivered to the combustion chamber, instead of introducing an additional amount of air directly into the chamber, and with this end in view I have devised a method and apparatus by which the entire amount of air is introduced into and thoroughly mixed with the fuel particles so that when delivered to the combustion chamber each fuel particle is surrounded by a suflicient quantity of air to afford proper combustion therefor.

In order to facilitate an understanding of my'invention, I have illustrated in the accompanying drawings one practical and referred apparatus designed to carry out 31y improved method. Referring to the drawings- I Fig. 1 is a vertical sectional View through an apparatus embodying the principles of my invention. i s

Fig. 2 is an end view looking at. the left hand end of the apparatus shown in Fig. 1.

Figs. 3 and 4 are transverse sectional views on the lines 3-3 and 4-4 of Fig, 1.

Fig. 5 is an enlarged fragmentary view of one of the jet nozzles; and;

Fig. 6 is a sectional view through the nozzle shown in Fig. 5.

On the drawin s, reference character 7 indicatesla coal 0 ute or hop er in which the powdered fuel is stored an from which it feeds downwardly to a screw conveyor 8 rotatably mounted in suitable bearings and adapted to operate in a suitable housing -in a housing 14.v

9. This conveyor comprises a shaft 11 provid'ed with a worm whichlis driven from a motor 12 or other suitable driving means.

At its delivery end the screw conve or is adapted to deliver the powdered fuel ongi- 'tud inally into the interior of a cylindrical screen 13 preferabl stationaril mounted the screen by the conveyor is there subjected to the action of alplurality of jets of air under pressure introduced radially into the stream of fuel being delivered into the houshe fuel delivered into' ing 14 through a connection 15 which is connected with any suitable source of 'air supply under pressure. The bottom of the screen'is provided with an outlet port 16 off-set relatively to the inleticonnection 15, f

and through this port the'commingled air and fuel are discharged from the screen through'a. pipe 17 into the mixer proper.

Thismixer consists primarily of a cylindrical conduit 18 and a surrounding casing 19'providing an air chamber 21 around the conduit to which air is supplied, under a pressure considerably in excess of the'pressure of the air and fuel delivered to the conduit, from any suitable source of air supply under pressure through the intake connection 22. The stream of -air and fuel traveling longitudinally through the con- 'duit 18 under pressure is subjected in the tudinal axes disposed substantially perpendicular to the longitudinal axis of the conduit, with the result that the flat jets of air are projected with their flat sides opposed to the traveling stream of air and fuel in the conduit. so that these jets break u and agitate-the stream of fuel and air, facilitating further mixing. Any desired number of these fiat jet nozzles may be utilized, but I have found that an odd number, preferably 5, is very satisfactory, arranged so that no two nozzles are directly opposed to each other.

Beyond the flat radial jet nozzles the conduit is equipped with a. plurality of circumferential rows of smaller nozzles 24:. The structure of these nozzles is most clearly shown in Figs. 5 and 6 and each nozzle is turned in the general direction of the travel of the stream of fuel and air through the conduit but at an angle of substantially 30 to the longitudinal axis of the conduit and toward the center of the conduit so that the issuing jets of air have a tendency to travel inwardly and spirally of the conduit. In order to effect a complete mixing and to overcome a uniform spiral travel of the stream in the conduit, the nozzles in each circumferential row are arranged in alternation, one,

nozzle being disposed to direct its jet to the right, for instance, and the next adjacent nozzle being disposed to direct its jet to the left with the result that the issuing jets are dischar ed in cross-firin relation and in non axial p anes. The nozz es in adjacent rows are also staggered with relation to the nozzles in the next row so that the combined action of the nozzles sets up a series of cross-currents which produce eddies and agitation in the traveling stream of fuel and air which thoroughly mixes and mingles the particles 'of fuel w1th the air. When the fuel issues from the delivery end of the conduit it is thoroughly and completely mingled with the requisite amount of air to support combustion and in this condition. it is delivered through the delivery nozzle 20 into the combustion chamber 26. The speed of delivery of the mixture from the nozzle 20 being greater than the rate of flame propagation, a flareback from the combustion chamber into the burner is prevented.

From the foregoing it will be observed that the fuel is first subjected in the screen 13 to the action of a plurality of inwardly directed jets of air so that it is preliminarily mixed. with a sufficient quantity'of the air to freely flow under pressure into the final mixer Where the stream of separately mixed fuel and air is first subjected to the agitating action of the flat radial jets of air and then it is subjected to the action of a large number of smaller jets which enter the conduit Letters complete and uniform mixing of the fuel with all of the air required to effect complete combustion of the fuel in the combustion chamber.

I claim:

1. The method of feeding powdered fuel which consists in subjecting a mass of fuel to a plurality of streams of air under pressure, causing the resultant mixture of fuel and air to travel in a cylindrical stream and introducing into said stream at an oblique angle to the direction of travel thereof and in non-axial planes a, plurality of jets of air under pressure.

2. The method of feeding powdered fuel which includes discharging obliquely to the direction of travel of, and in non axial planes into, a flowing mixture of air and fuel, a plurality of jets of air.

3. Themethod of feeding powdered fuel which consists in discharging obliquely into a flowing stream of fuel mixture, a plurality of jets of air disposed in non-axial planes directed alternately on opposite sides of the longitudinal axis of said stream.

4. In a powdered fuel feeder, the combination of a cylindrical conduit, an air chamber surrounding said conduit, means for introducing a plurality of jets of air radially into said conduit, and means for introducing a plurality of jets of air into said conduit at an oblique angle to the longitudinal axis thereof.

5. In a powdered fuel feeder, the combination of a cylindrical conduit, an air chamber surrounding said conduit, and a. plurality of nozzles for delivering air under pressure from said chamber into said conduit,-one set of nozzles being arranged to deliver radiallyinto the conduit and another set being mounted to deliver at an angle to the radii of the conduit and in non-axial planes.

6. In a powdered fuel feeder, the combination of a cylindrical conduit adapted to contain a mixture of fuel and air, a series of nozzles arranged to discharge flat jets of air radially into said conduit, and a series of nozzles arranged to discharge obliquely into said conduit in cross-firing relation.

in intersecting relation, thereby setting up cross-currents and eddies which result in a MILTON lV. ARROWOOD. 

